High dose intravenous methotrexate and reversible focal neurological deficit

Correlation of cerebrospinal fluid beta-glucuronidase activity with plasma methotrexate concentrations in leukemic children receiving high-dose methotrexate

BACKGROUND

The activity of lysosomal enzymes is increased in body fluids during inflammation, in which cellular malfunction and cellular death occurs. Because chemotherapy also causes cell malfunction and death, for identifying a neurologic effect, we studied the activity of beta-glucuronidase in the cerebrospinal fluid (CSF) of leukemic children during treatment.

PROCEDURE

The beta-glucuronidase activity in CSF was determined in 13 patients with B-precursor acute lymphoblastic leukemia (ALL) treated with the medium risk arm of ALL Berlin-Frankfurt-Munster (BFM) 95 protocol. Plasma methotrexate (MTX) levels were determined at 24 and 48 hr after the infusion of high-dose (5 g/m(2)/24 hr) MTX (MCA phase).

RESULTS

The mean (SD) beta-glucuronidase activity prior to the onset of chemotherapy was 19.9 (5.6) nmoles/4-methylumbelliferone/ml/hr. No significant changes in activity were noted during the phases of the protocol except of the MCA3. The activity was 24.4 (6.8) on MCA2, 28.4 (9.3) on MCA3, and 24.1 (9.5) on MCA4. The beta-glucuronidase activity was positively correlated with the plasma MTX levels at both 24 hr (r = 0.483, P = 0.006) and 48 hr (r = 0.676, P < 0.0001). No progressive changes were noted during the different phases of the protocol. The greatest beta-glucuronidase activity was measured in two patients with neurotoxicity.

CONCLUSIONS

The beta-glucuronidase activity is increased in the CSF of leukemic children receiving high-dose MTX and particularly in neurotoxicity. It is positively correlated with plasma MTX levels. No cumulative effect of the chemotherapy was observed. The increased beta-glucuronidase activity is most likely due to enzyme leakage through the cell membranes caused mainly by a toxic effect of MTX on the cells of the central nervous system (CNS).

Proton magnetic resonance spectroscopy ((1)H-MRS) of the brain following high-dose methotrexate treatment for childhood cancer

BACKGROUND

To avoid the late sequelae associated with cranial radiation therapy in childhood, intermediate- or high-dose intravenous methotrexate (HDMTX) has found increasing application as a means of preventing the development of overt central nervous system disease in childhood acute leukaemia. However, acute and chronic neurotoxicity has been described following HDMTX therapy, and the long-term intellectual outcome in children treated in this way is inadequately documented. Proton magnetic resonance spectroscopy ((1)H-MRS) of the brain is a noninvasive, quantitative way of assessing aspects of cerebral metabolism, which has not previously been applied to the study of children undergoing central nervous system directed therapy.

PROCEDURE

To evaluate the potential role of (1)H-MRS in the investigation of related neurotoxicity, 11 children who had received HDMTX (cumulative dose 6-96 g/m(2)) underwent localised (1)H-MRS, magnetic resonance imaging. Neuropsychological assessments were performed on the children who had more than 1 year of follow-up time since last methotrexate treatment. Control (1)H-MRS studies on 11 adult and 6 young volunteers were undertaken. Eight patients had spectra of adequate quality. Comparisons between (1)H-MRS metabolite ratios and normal controls were made.

RESULTS

Patients had a low choline/water ratio compared to controls (P < 0.01). No differences between patient and control NAA/water, Cr/water, Naa/Cr, and Cho/Cr ratios were seen. Overall, 3 patients had abnormal white matter changes on MRI. The mean IQ of the patients (104.1) was in the normal range.

CONCLUSIONS

It is postulated that choline depletion in the brains of these patients may reflect subclinical disturbances of myelin metabolism as a result of methotrexate therapy and may represent a possible avenue of treatment in patients with clinical chronic methotrexate-related neurotoxicity.

Side effects of immunosuppressant therapies used in neurology

This article provides an overview of the clinically relevant complications of the main immunosuppressants currently used in the treatment of neurologic disorders with suspected or established immune etiology. The most serious complications are discussed in detail, including pathophysiology and preventative measures. An intimate knowledge of these complications proves helpful in the day to day practice of the neurologist supervising immunotherapy.